In total knee replacement surgery, it is known to use instrumentation to guide the cuts made to the proximal tibia and the distal femur in order to properly align the cuts with the bone.
For example, U.S. Pat. No. 4,524,766 describes a system of precision instruments for utilization in knee surgery. The instrumentation provides a series of alignment and cutting guides which function to align the various necessary cuts of the bone structure with respect to the various body parts. FIG. 7 of that reference as well as FIG. 15 shows certain interrelational instrumentation used in aligning the cuts, in particular, the distal femur cut and the proximal tibia cut.
U.S. Pat. No. 4,938,762 refers to a reference system for implantation of condylar total knee prostheses. This device involves a cumbersome set of reference systems used for total knee prostheses which comprises a measuring rod which is parallel to the longitudinal axis of the tibia which has a pair of attachment arms for attachment to the tibia. A guide rail is connected to the measuring rod having a scale thereon and an adjustable measuring carriage to which a cutting block for performing the necessary osteotomies is affixed for movement in two directions. Of particular interest with respect to the present application is FIG. 2 of that reference and the accompanying text.
U.S. Pat. No. 4,574,794 is entitled, "Orthopaedic Bone Cutting Jig and Alignment Device". This device constitutes a large cumbersome frame which attaches to the lower extremity of the leg and adjusts for the alignment of the various bone cuts.
U.S. Pat. No. 4,421,112 describes a tibial osteotomy guide assembly and method. That reference is described as having a method and guide assembly for use in tibial osteotomy wherein two pairs of guide pins are inserted into the tibia at predetermined angles with respect to each other through a guide block. The adjacent surfaces of the pairs of pins are then used to precisely guide a saw by which a wedged shape segment of the tibia is removed.
U.S. Pat. No. 4,487,203 entitled, "Tri-Planer Knee Resection Method" describes as apparatus for use in a tri-planer knee system which includes a single guide member for use in resecting the distal femur condyles, the proximal tibia and the distal femur. The instrumentation includes femur and tibia guide rods, a tibia adapter, a tibia bar and a femur bar for establishing equal flexion and extension gaps in tri-planer resection.
U.S. Pat. No. 4,567,885 entitled, "Tri-Planer Knee Resection System" describes a tri-planer knee resection system which is provided for preparing a knee joint for a prosthesis. This patent matured from an application which was a division of the application which matured into the '203 patent above.
U.S. Pat. No. 4,722,330 entitled, "Femoral Surface Shaping Guide for Knee Implants" describes a guide for mounting on an intermedullary alignment guide which references the central long axis of the femur in shaping the distal femoral surface and a method for shaping the distal femur using the shaping guide.
U.S. Pat. No. 4,892,093 entitled, "Femoral Cutting Guide" describes a cutting guide which is used for guiding a saw blade during the preparation of a femur for the implant of the femoral component of a knee prosthesis. The guide includes guide surfaces for enabling the cutting of all four of the anterial femoral cut, the posterial femoral cut, the anterior chamfer and the posterior chamfer, while the cutting guide remains located and secured to the femur in a single position.
U.S. Pat. No. 4,926,847 entitled, "Surgical Cutting Block" issued previously to the present inventor. That device provided a significant advance in the development of cut saw guides for knee surgery and provided a cutting guide to position a bone cutting device. The cutting guide has at least one fixed or stationary surface and a movable surface to create a slot or gap between the fixed surface and the movable surface. The cutting device is positioned and held in the slot to make accurate bone cuts.
While the above-described devices have provided mixed results in the advancement of the surgical technique in total knee prostheses replacement, it has been found that when doing less radical single condyle replacement that the interrelationship between the two surfaces, that is the proximal tibial surface and the distal femur surfaces, is difficult to align. That is, in a single condyle replacement, the remaining healthy condyle is left in tact as well as the receiving tibial tray on the proximal tibia. Only the diseased portion of the single condyle is removed. Thus the new condyle prosthesis must be aligned not only with the reference to the mechanical axis of the patient but also with respect to the condyle which remains in tact and unchanged by the surgery.